Resilient floor coverings, which include for example vinyl tiles and vinyl sheet, are well known. There are described for example in an article entitled “Flooring Materials” in Encyclopaedia of Polymer Science and Engineering, Wiley-Interscience, Volume 7 (1987), pages 233-247.
Such floor coverings, as described in the above article, are composite materials. The uppermost film, which is commonly called the wear layer, is formulated for good resistance to abrasion and wear. The undermost film of the composite is commonly referred to as the backing film and may comprise one or more backing layers. A printed patterned film is generally interposed between the wear layer and a first backing layer.
The backing layer is generally a highly filled thermoplastic material. The compositions of all of the layers in the composite must be balanced to ensure that the floor covering has the correct properties, for example insulating and sound absorbing properties, and in particular freedom from a tendency to curl. Economic factors must also be borne in mind.
In the manufacture of resilient floor coverings, films, including the backing layers, are commonly made by techniques such as calendaring, extrusion and spread coating.
In the field of resilient floor coverings, as in all consumer led fields, there is a constant drive to provide high quality products at ever lower prices. Manufacturers can reduce costs as far as possible by negotiations with suppliers and looking carefully at their production processes but there may also be changes to products that can be made to reduce the cost of the product itself.
In the field of resilient floor coverings increasing the level of filler in one or more of the films of the product can greatly reduce the cost of producing the product. However, increasing levels of filler has associated problems that must be considered, for example high filler levels can introduce curl into the final product and can affect the dimensional stability of the film and the end product. There can also be problems in actual manufacture of the film as high filler levels can result in processing problems, whether calendaring, extruding or spread coating.
In the field of floor coverings manufactured using plastisol processes it is simpler to insert a fibrous scrim between the printed patterned film and a highly filled backing film. The scrim allows the use of a highly filled, and therefore cheaper, backing film without any adverse effect on the curl and dimensional stability of the end product.
However, the use of a scrim in a calendaring, extrusion or spread coating process would add further steps and cost to the production of the product and gives fewer advantages in this particular production method. There therefore remains a need for a way to both reduce the cost and negate curl in resilient floor coverings, particularly those manufactured by a calendaring, extrusion or spread coating process.